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It sepends on the actual input impedance of the mic preamp. For a typical 2kohm input impedance, the capacitor should be 1.15uF for 70Hz cut-off. The actual response would be first-order, i.e. only

I literally took the .lib file provided by TI, which defines the SUBCKT and appended my SBCKT to it. Yes. My intention was to account for all the pins with the parameters already defined in the .lib

Got it, thank you much. Then, what should be the capacitor value to cut off audio at frequencies lower than 70Hz? Thanks again.

Hold on, did you also define the SUBCKT for OPA164x??? I presume you did since this is what TI provides. But I want to make sure. Basically, what you've done is to "call" two versions of the

I'm having fun with variations on the OPA Alice circuit and would like to be able to model using SPICE in KiCAD. I found the model on TI's website but it doesn't have the correct subcircuit for a

In order to work, it takes disconnecting one of the internal 6.81k resistors inside the preamp, or to isolate it DC-wise, which is exactly what teh capacitor does.

A couple of years ago, Martin Kantola shared his simple P48 without a capacitor. Pure genius! Do a search for: One resistor P48 electret mic Different pros and cons compared to SimpleP48.

Tj=he role of the capacitor is to conduct AC signal whilst isolating DC. Not used, as in "not there" or as in "replaced with a short"? In the former case, very low signal, in the latter case, too low

The capacitor blocks the 48V to your mic. The 48V via pin 3 is limited to a safe voltage by the resistor. Smaller values will make a 6dB/octave HP filter in the audio range. Mostly nor desired.

Dear All, My questions are, In the simpl48 circuit, what is the role of the capacitor? What happens if it is not used? What are the results at different values? Many thanks.

This method is valid for unbalanced loads, but not for all types of balanced loads.. This is true only if the outputs are non-floating, which is the case of the typical Schoeps arrangement, or

Try this method shown in a Jensen Tranformer app-note: https://www.jensen-transformers.com/wp-content/uploads/2014/08/as048.pdf That will work for an active output microphone if you measure the

"Earthworks Homepage's M23R Spec : OUTPUT IMPEDANCE ? ?65Ω balanced (between pins 2 & 3)" That means exactly what it states, that the output signal is taken between pins 2 and 3, and the impedance

Thanks Jerry, I thought it was 1K. I worked in Marketing for a decade... Medical Devices. And there was the FDA... ;-) Jules <jerryleemarcel@...> wrote:

In the absence of a comment saying different, impedances are measured at 1kHz. Some manufacturers indicate that impedance may vary over the audio range. Anything the mktg dept deems

Question for the group on this. What is the correct frequency to measure the output impedance? I am assuming referenced to 1Khz. Or should it be 20hz to 20Khz? What do manufacturers spec? I checked

I'm trying to get in touch with David Searle, aka Zephyr on MicBuilders. David, if you are still looking in occasionally, the email address I have for your no longer works. My old email address no

Dear Jerry, Thanks to your reply. Earthworks Homepage's M23R Spec : OUTPUT IMPEDANCE ? ?65Ω balanced (between pins 2 & 3) This is the specification provided on the website. What I mean here is

It seems correct, indicating a mic impedance of about 130 ohms.

Dear Jerry, I’m still getting similar results. R1 : 66 Ohm R2 : 65 Ohm Here’s my question: I’m using a single potentiometer to control both channels (R1 and R2), meaning adjusting it changes